I suggest you replace the CTS and the T-stat. Worked for me.

I'm on my third thermostat. It still does it. Where and what is the CTS?

Coolant Tempreture Sensor I believe.. I don't know exactly where it is.. it might be on the passenger side of the radiator ???? :?: Never checked.. putting out "GEARHEAD" bat signal

So far to try to solve this:
1)changed the temp sensor - no change.
2)changed the IAC - no change.
3)cleaned the throttle body - no change.
4)changed upper intake and upper and lower gaskets - no change.
Thats why I'm thinking it is something in the programming of the car at cold start below 45 deg.
What else could it be? vac. leak? very annoying in winter.
All summer it works like a dream....

Try 2 things.. pluggin in to block heater.. if that helps some.. it MIGHT be the oil.. I doubt it.. but I notice my car idles lower during warm ups now.. I was a retarde before and added in 15W-40 by accident last winter.. *long story.. guess I shouldn't change oil drunk and hung over* and I notice my warm idle is high.. I have now put in 0w-30 and during warm ups it'* 150~200 RPM lower then with 10w-30

Seems odd that we would both have the same issue due to oil weights...but I'll try anything!! I currently run 10w-30 Castrol.

Well.. I don't know if it would help in this case.. but if SSEBONNE4EVA has changed so many parts.. and is fine after warm up, then its the only thing I can think of. Next to seal issue ( when engine is warm or up to temp things expand and possibly seat better with each other )

I'm running 10w-30 Quaker State friction reducing formula.
I guess I could try 5w-30 on my next oil change in about a week.
Just don't see the connection to the PCM holding RPMs @1500 and motor oil.

I notice when I had my car'* front on ramps last night.. I let it sat there like that for 2 hours or so. Then I started it up.. It jumped to 1500 RPM and then slowly came down.. so I"m thinkin.. with the front end jacked up.. whats the difference? Other then fuel delivery? ( pressure )..

I"m really stumped as to why your car revs so hi.. especially if you said your IAT has been replaced.. have you attempt to get the ohms reading to ensure it'* reading correctly?

Here.. try this

http://www.bonnevilleclub.com/techinfo/?article=87